1. Field of the Invention
The present invention relates to an electronic device including a speaker, such as an electronic dictionary, a mobile phone, or a personal digital assistant (PDA).
2. Description of the Related Art
As a mounting structure for a speaker in a mobile phone, a structure is known in which a speaker unit is provided on a circuit board inside a device case, a contact sheet having a plurality of contact sections is provided on the circuit board, a key sheet having a plurality of key tops is provided on the contact sheet and each key top of the key sheet is exposed from the surface of the device case, as described in Japanese Patent Application Laid-Open (Kokai) Publication No. 2005-236894.
In amounting structure for a speaker such as this, a sound emitting hole is provided in a key top of the key sheet in an area corresponding to the speaker unit, as well as in a contact section of the contact sheet in the area corresponding to the speaker unit, in order to emit sound generated in the speaker unit from the device case.
However, there is a problem in this conventional mounting structure for a speaker in that the thickness from the front surface of the key top to the undersurface of the speaker unit is large and therefore the thinning of the device cannot be achieved.
In addition, there is another problem in this conventional mounting structure for a speaker in that sound generated in the speaker unit cannot be satisfactorily emitted outside from the device case.
Although a mounting structure has been developed in which the contact sheet between the speaker unit and the key sheet is arranged underneath the speaker unit, and the speaker unit is placed closer to the key tops of the key sheet, there is a problem in that sound generated in the speaker unit is not emitted from only the sound emitting hole in the key top because it leaks to the surrounding area of the speaker unit.
As described above, in the conventional mounting structure for a speaker, a structure has been adopted in which a speaker unit is provided on a circuit board. Accordingly, the contact sheet is required to be provided on or underneath the speaker unit, and therefore the overall thickness cannot be made sufficiently thin.